The measurement of characteristics of light, such as radiance, luminance, reflectance, transmittance, contrast, color, color temperature, spectral power distribution, illuminance, etc. is useful for a wide range of applications. Example of such applications include, but is not limited to, photography, displays (e.g., CRT, LED, or plasma displays), room lighting and lamps, instrument panels, roadway lighting, automotive lighting, airport lighting, specimen analysis, dental/medical analysis (e.g., tooth color, tissue analysis, DNA analysis, eye analysis, skin analysis, etc.), chemical analysis (material/compound analysis), textile & paint color analysis and matching, water/ocean/lake pollution analysis, wine vintage analysis, and the like.
A variety of detectors can be used to observe the desired properties of the light. Photomultiplier tubes (PMTs), photodiodes and other single channel light detectors have been used in photometry. Such detectors may be selected to simulate the light response of the human eye, with or without filters. Multiple channel light detectors, such as arrays of detectors, can be used for colorimetry, spectrophotometry, and spectroradiometry. Such arrays include arrays of photomultiplier tubes, as well as self scanned arrays, such as photodiode arrays, CMOS arrays, charge-coupled device (CCD) arrays, and the like.